Swift: Opening a file by drag-and-drop in window - macos

Question

In Swift, how can I build an area in a window of my Mac app where a user can drag-and-drop a folder onto this area, and have my app receive the path of the folder?
In principle, it seems to me that this is a similar concept to Apple's CocoaDragAndDrop example app. I've tried to work my way through understanding that source code, but the app is written in Objective-C and I've not successfully managed to replicate its functionality in the app I am building.
Thank you in advance.

Answer 1

In a custom NSView:
override init(frame frameRect: NSRect)
{
super.init(frame: frameRect)
registerForDraggedTypes([kUTTypeFileURL,kUTTypeImage])
}
override func draggingEntered(sender: NSDraggingInfo) -> NSDragOperation
{
println("dragging entered")
return NSDragOperation.Copy
}
The catch is, to get it working I had to put that custom view as a leaf and the last view in the storyboard

Answer 2

This worked for me (on a NSWindow subclass):
In awakeFromNib:
registerForDraggedTypes([NSFilenamesPboardType])
Then add the following operations (at least draggingEntered and performDragOperation) to the window (or view):
func draggingEntered(sender: NSDraggingInfo) -> NSDragOperation {
let sourceDragMask = sender.draggingSourceOperationMask()
let pboard = sender.draggingPasteboard()!
if pboard.availableTypeFromArray([NSFilenamesPboardType]) == NSFilenamesPboardType {
if sourceDragMask.rawValue & NSDragOperation.Generic.rawValue != 0 {
return NSDragOperation.Generic
}
}
return NSDragOperation.None
}
func draggingUpdated(sender: NSDraggingInfo) -> NSDragOperation {
return NSDragOperation.Generic
}
func prepareForDragOperation(sender: NSDraggingInfo) -> Bool {
return true
}
func performDragOperation(sender: NSDraggingInfo) -> Bool {
// ... perform your magic
// return true/false depending on success
}

Answer 3

my 2 cents for OSX - swift 5 (and fixed for loading from XIBs/storybord.)
// Created by ing.conti on 31th jan 2020.
//
import Cocoa
class AnalysisView: NSView {
override init(frame frameRect: NSRect)
{
super.init(frame: frameRect)
self.registerMyTypes()
}
required init?(coder: NSCoder) {
super.init(coder: coder)
self.registerMyTypes()
}
final private func registerMyTypes()
{
registerForDraggedTypes(
[NSPasteboard.PasteboardType.URL,
NSPasteboard.PasteboardType.fileURL,
NSPasteboard.PasteboardType.png,
NSPasteboard.PasteboardType.fileNameType(forPathExtension: "wtf")
])
}
override func draggingEntered(_ sender: NSDraggingInfo) -> NSDragOperation {
print("draggingEntered")
return NSDragOperation.copy
}
override func prepareForDragOperation(_ sender: NSDraggingInfo) -> Bool {
let allow = true // check your types...
print("prepareForDragOperation")
return allow
}
override func performDragOperation(_ sender: NSDraggingInfo) -> Bool {
let pasteBoard = sender.draggingPasteboard
print("performDragOperation")
if let urls = pasteBoard.readObjects(forClasses: [NSURL.self]) as? [URL]{
// consume them...
print(urls)
return true
}
return false
}
}